Wave effects in the microlensing of pulsars and FRBs by point masses

Understand

Wave effects are often neglected in microlensing studies; however, for coherent point-like sources, such as pulsars and fast radio bursts (FRBs), wave effects will become important in their gravitational lensing.

• In this paper, we describe the wave optics formalism, its various limits, and the conditions for which these limits hold.
• Using the simple point lens as an example, we will show that the frequency dependence of wave effects breaks degeneracies that are present in the usual geometric optics limit, and constructive interference results in larger magnifications further from the lens.
• This latter fact leads to a generic increase in cross section for microlensing events in the wave-optics regime compared to the geometric optics regime.